1. Field of the Invention
The present invention relates to an image forming apparatus and a recovery method, and more particularly, it relates to an image forming apparatus comprising a recording head, and a recovery method.
2. Description of the Related Art
In ink jet recording apparatuses for office and home applications which have been popularized in the market, since liquid ink is used for recording, an ink discharge surface of an ink jet recording head must be wiped. In this case, generally, a wiping operation is controlled on the basis of dot count. For example, Japanese Patent Application Laid-Open No. 1-71758 (1989) discloses a technique for wiping and cleaning an ink discharge surface of an ink jet recording head when a predetermined dot number is counted.
Further, Japanese Patent Application Laid-Open No. 7-125228 (1995) and No. 2-141248 (1990) disclose a wiping sequence optimized by using both a timer and dot count.
In these techniques, by detecting contamination on the ink discharge surface of the recording head by the dot count and by ascertaining adhered and viscosity-increased ink by the timer, needless or excessive wiping effected in a less wet condition generated when the wiping is controlled by the timer alone and increase in ink viscosity caused if low duty is continued when the wiping is controlled by the dot count alone are prevented.
By the way, although the wiping itself is required for preventing the wetting of the ink discharge surface of the ink jet recording head and poor recording due to contaminant such as dirt, since the wiping is effected by rubbing the ink discharge surface of the ink jet recording head by means of a wiper member, depending upon various conditions such as an urging force, hardness of the wiper member, a wiping speed and the like, recording quality may be deteriorated due to deterioration of water repelling processing of the ink discharge surface of the ink jet recording head and damage of discharge ports of an ink discharge nozzles.
Further, the ink discharge surface of the ink jet recording head is generally formed from stainless steel, brass, glass or polysulfone/phenol resin. In many cases, although the ink discharge surface is formed from material having hardness greater than that of rubber, as the case may be, an ink droplet removing ability during the wiping may be reduced due to wear of the wiper itself, which results in poor ink discharging. Accordingly, although the wiping operation is required when the recording is effected by using the ink jet recording head, it is desirable that the frequency of the wiping operation be reduced as much as possible.
However, in the above-mentioned conventional techniques, since the wiping is effected before the ink jet recording head is capped, although the wiping based on the recording operation is not effected if the recording is effected with a small dot number, the wiping is ultimately effected when the capping is effected after the recording, and, thus, the wiping does not reach the required dot number, and actually, a similar operation when the lesser dot number is set as a threshold value for controlling the wiping operation will be effected. Namely, in the above-mentioned conventional techniques, the wiping operation may be effected at a timing which does not require the wiping operation, and, if such unnecessary wiping operations are repeated, the recording quality will be deteriorated.